The group on Thursday decried the policy affecting some 1,600 unreinforced masonry buildings that are on average 90 years old, many in areas with a predominantly black population, The Oregonian/OregonLive reports.

The policy "exacerbates a long history of systemic and structural betrayals of trust and policies of displacement, demolition, and dispossession predicated on classism, racism, and white supremacy," the group said.

The NAACP said the policy will make it tougher for owners of brick buildings to get loans and will discourage investment. It says that means buildings will have to be sold, and that developers will demolish and redevelop, increasing the cost to live there and forcing current residents out.

"It speaks to our houses of worship and everything about the black presence in the North-Northeast area," said the Rev. E.D. Mondaine, a pastor at Celebration Tabernacle Church in north Portland and president of the Portland NAACP chapter.

City officials say the ordinance approved in October is part of an effort ultimately aimed at upgrading old buildings to withstand an earthquake, though seismic upgrades likely wouldn't be required for at least 20 years. Such upgrades could cost brick-building owners millions of dollars.

Experts say Portland is at risk because there's close to a 50 percent chance of a giant earthquake along the Cascadia Subduction Zone off the Oregon coast in the next 50 years.

The warning signs and a requirement that building owners must file a record of compliance is "really just a disclosure," said Alex Cousins, a spokesman for the city Bureau of Development Services. "That's the purpose behind it."

The warning signs are to go up on public buildings this month, and on most other buildings by March 1. The warning on them says: "This is an unreinforced masonry building. Unreinforced masonry buildings may be unsafe in the event of a major earthquake."

In related action, a nonprofit coalition of Portland brick building owners recently filed a lawsuit seeking to block the ordinance, arguing it's unconstitutional under free-speech and due-process rights.

"The government is forcing private property owners to basically broadcast the government's message instead of their own," said John DiLorenzo, an attorney for the group.

Also, a coalition of music venues called MusicPortland has sided with the NAACP, saying the ordinance threatens some 30 of its music venues.